The unusual minimum of sunspot cycle 23 caused by meridional plasma flow variations

Direct observations over the past four centuries show that the number of sunspots observed on the Sun's surface varies periodically, going through successive maxima and minima. Following sunspot cycle 23, the Sun went into a prolonged minimum characterized by a very weak polar magnetic field and an unusually large number of days without sunspots. Sunspots are strongly magnetized regions generated by a dynamo mechanism that recreates the solar polar field mediated through plasma flows. Here we report results from kinematic dynamo simulations which demonstrate that a fast meridional flow in the first half of a cycle, followed by a slower flow in the second half, reproduces both characteristics of the minimum of sunspot cycle 23. Our model predicts that, in general, very deep minima are associated with weak polar fields. Sunspots govern the solar radiative energy and radio flux, and, in conjunction with the polar field, modulate the solar wind, the heliospheric open flux and, consequently, the cosmic ray flux at Earth.     

河南省地质现象的旅游资源化和效益化过程

地质旅游资源是一种新型的、合乎现代时尚的旅游资源.地质旅游资源的开发是一项系统工程.河南省具有十分丰富的地质现象,相应的也具有十分丰富的地质旅游资源.河南地质旅游资源的开发要完成两个转变:一是从地质现象转化为地质旅游资源——即资源化过程;二是把地质旅游资源转化为经济效益——即效益化过程.作者提出了资源化过程的原则和方法以及效益化过程的两步开发战略.     

On the mechanism of inhibition of p27 degradation by 15-deoxy-Δ12,14-prostaglandin J 2 in lymphoblasts of Alzheimer’s disease patients

It has been proposed that neuroinflammation, among other factors, may trigger an aberrant neuronal cell cycle re-entry leading to neuronal death. Cell cycle disturbances are also detectable in peripheral cells from Alzheimer’s disease (AD) patients. We previously reported that the anti-inflammatory 15- deoxy-Δ^12,14-prostaglandin J ₂ (15d-PGJ ₂) increased the cellular content of the cyclin-dependent kinase inhibitor p27, in lymphoblasts from AD patients. This work aimed at elucidating the mechanisms of 15d-PGJ ₂-induced p27 accumulation. Phosphorylation, half-life, and the nucleo-cytoplasmic traffic of p27 protein were altered by 15d-PGJ2 by mechanisms dependent on PI3K/Akt activity. 15d-PGJ ₂ prevents the calmodulin-dependent Akt overactivation in AD lymphoblasts by blocking its binding to the 85-kDa regulatory subunit of PI3K. These effects of 15d-PGJ ₂ were not mimicked by 9,10-dihydro-15-deoxy-Δ^12,14- prostaglandin J ₂, suggesting that 15d-PGJ ₂ acts independently of peroxisome proliferator-activated receptor γ activation and that the α,β-unsaturated carbonyl group in the cyclopentenone ring of 15d-PGJ ₂ is a requisite for the observed effects. Received 14 July 2008; received after revision 2 September 2008; accepted 12 September 2008     

Multiple paths to aquatic specialisation in four species of Central American Anolis lizards

Aquatic anoles present an interesting ecomorphological puzzle. On the one hand, the link between habitat use and morphology is well established as convergent within the Caribbean anole radiation. On the other hand, aquatic anoles do not appear to form an ecomorphological group – rather, it appears that there may be several ways to adapt to aquatic habitats. We explore this issue by examining the ecology, morphology and performance of four species of Central American aquatic anoles belonging to two different lineages. Overall, we find that aquatic anoles overlap in multiple ecological and morphological dimensions. However, we do find some differences in substrate use, claw and limb morphology, and bite force that distinguish Anolis aquaticus from the other three species (A. lionotus, A. oxylophus and A. poecilopus). Our results suggest that A. aquaticus is adapted to climb on boulders, whereas the other species utilise vegetation in streamside habitats.     

可降解下腔静脉滤器的生物力学性能及有限元分析

利用有限元分析和径向支撑力测试,分析不同支撑杆数目对新型生物可降解下腔静脉滤器（inferior vena cava filters, IVCF）的生物力学性能的影响。应用三维建模软件建立支撑杆数目为8, 10, 12的IVCF模型;通过室温拉伸左旋聚乳酸得到其应力-应变曲线,使用Abaqus软件模拟分析3种支架在压握和自扩张过程中的生物力学性能;同时将3种IVCF进行径向支撑力测试。结果表明,3种支架的应力峰值不同,但应力分布趋势相同;其径向支撑力随支撑杆数目的增加而减小,自扩张性能则与之相反;10杆IVCF表现出较好的综合力学性能,经压握后不仅有足够的径向支撑力,而且可以实现自我扩张,对血管壁的损伤最小。     

X射线荧光光谱法测定海底钴结壳的方法研究

采用粉末压片制样,X-射线荧光光谱法直接测定钴结壳中Fe、Mn、Co、Ni、Si、Al、Ca、K、Na、Ti、P、Mg、Cu、Pb、Mo、Sr、V、Zn、Zr、Y、Ba等元素。重点讨论用熔融法定值部分样品,然后用加以定值的钴结壳标准及样品、国家岩石、土壤、水系沉积物系列标准用粉末压片制样,做工作曲线,一次测量钴结壳中二十余种元素,并用定值样品做精密度与准确度试验,各元素统计结果为RSD％（n=12）除V的RSD〈4％外,其余元素的RSD均小于2％,测定结果与标准值和ICP-MS测量值相符。     

VOx·nH2O纳米管的制备及表征

通过表面活性剂乳化剂OP-10/十八胺作为软模板在水热条件下合成均一、超长VOx·nH2 O纳米管.纳米管长5-15μm,外径为100-120mm,内径10-20nm.所得产物用X-射线衍射(XRD)、透射电子显微镜(TEM)高分辨电子显微镜(HRTEM)进行表征,并对其反应机理进行了研究.     

Mechanochemical synthesis and high-capacity performances of transition-metal borides as aqueous anode materials

Transition-metal borides MB0.5(M = Co,Mo,V) were synthesized by high-speed mechanical ball-milling of the corresponding elemental metals and boron,and investigated as aqueous anode materials.The as-synthesized borides can achieve an excellent discharge capacity,about twice that of their parent transition metals.The metal boride electrodes also exhibit polarizations about 100-300 mV lower than those of their parent metals.The galvanostatic discharge curve of CoB0.5 shows a single discharge voltage plateau as a result of simultaneous electro-oxidation of elemental cobalt and/or amorphous cobalt boride.Both MoB0.5 and VB0.5 show two well-defined voltage plateaus,corresponding to the electro-oxidation of the corresponding metal and boride.These results show that the coexisting transition metal and boride in the metal borides co-activate each other in the ball-milling process,thereby significantly enhancing their electrochemical performances.     

THE INFLUENCE OF DRAWING CONDITIONS OF PET POY ON STRUCTURE AND PROPERTY OF THE FIBER

Drawing tests upon PET POY have been made by using dynamic thermal stress analyser,which show that the dynamic thermal stress of fiber is readily affected by drawing conditions. Aseries of samples have been obtained under different drawing velocities, drawing temperatures anddraw ratios. The variations of structural factors of fiber such as the orientation, crystallinity,crystallite size and the thermal shrinkage have been measured. It is proved through experimentsthat the thermal shrinkage(Y) of the drawn fiber of PET POY is influenced by the orientation (rep-resented by sonic velocity x_1) and crystallinity (x_2) of the fiber. The quantitative relationship is es-tablished using the binary regression method: Y=10.2246+2.2030x_1-26.2670x_2 The mechanical properties such as tenacity, elongation, yield stress, initial modulus and the te-nacity at 10% elongation, etc. have also been measured. The relations between the tenacity at 10%elongation (D) and drawing velocity(V), draw ratio (DR), drawing temperature (T), and sonic ve-locity and crystallinity have been obtained using a method of mathematical statistics: D=4.594-0.009 6V , D=-8.937+7.170DR, D=2.866+0.00629T, D=-7.34+2.866x_1+6.314x_2 These equations fit well with data from the experiments. This work will be benefical to the control of quality of products and the development of newproducts.     

数学与广告

探讨了广告和数学的关系．阐述了数学概念、数学符号和数学方法在广告文体、广告策划、广告制作和广告评价中的应用．